PROJECT SUMMARY Millions of miles of water and sewer piping systems are currently buried across the United States. Near sites contaminated with hazardous wastes, pipe deterioration provides pathways for contaminant entry and transport to surrounding communities. One challenge of leaking sewer pipes near Superfund sites involves volatilization of contaminants that enter subsurface pipes, posing indoor inhalation exposure risks. In drinking water piping systems, pipe fractures coupled with pressure transients within the piping system allow subsurface contaminants to enter the system?especially at contaminated sites where such breaks become conduits impacting water quality. This project provides strategies to reduce and prevent exposure risks to environmental contaminants, especially chlorinated ethenes and per- and polyfluoroalkyl substances (PFAS) that result from leaking and damaged subsurface piping networks. The overarching project goal is to combine piping infrastructure science with fate and transport science to identify and reduce exposure risks associated with trichloroethene (TCE), tetrachloroethene (PCE), and PFAS. To achieve this goal, we propose three specific aims: 1) To measure mass flux of contaminants at field sites where TCE and PCE exposure risks are impacted by piping networks; evaluate flow and pressure field data from drinking water systems; and, determine the effect of broken or failed piping components and joints in lab settings 2) To develop models that: a) predict mass flux of contaminants to indoor air and evaluate exposure risks; b) predict mass flux of contaminants through piping networks; and, 3) To use stakeholder input and stochastic analyses to characterize model uncertainty and sensitivity in an effort to develop stakeholder-relevant solutions that reduce and prevent exposure risks. The specific aims integrate advanced computational modeling approaches with field measurements collected from piping systems in Eastern Kentucky and at a start-of-the-art vapor intrusion research facility near a Superfund site. Comparing data from different measurement techniques, including a novel sensor technology, provides information about temporal variability of sewer gas mass flux which is critical due to the high level of uncertainty that surrounds environmental exposure risks. The research team aims to bolster a paradigm shift in the way uncertain exposure risks are managed and develop solutions to reduce exposure risks in ways that are acceptable to communities. Risk communication science will inform strategies to evaluate uncertainty using stakeholder perspectives and evidence-based practices as a framework to promote solution-oriented research and environmental health literacy.